Handheld mobile devices, such as mobile phones (cell phones), PDAs, or any pervasive devices, are currently in wide use and are deemed indispensable electronic products. With mobile phones being increasingly robust, their operation is becoming more complicated. Mobile phones nowadays enable a wide variety of applications to be executed thereon and provide functions other than voice conversations, such as surfing the Internet. However, due to limitations of the dimensions of their screens and limitations of the quantity their keys, mobile phones nowadays are operated inefficiently and inconveniently, regardless of whether they are equipped with a touchscreen having a virtual keyboard. For example, to protect data stored on their smart-phones, some users set a password to lock their cell phones. To start using their phones, users enter the password to unlock the cell phones. Assuming that a driver wants to call a friend of his/hers with his/her mobile phone while driving a car, it is dangerous and inconvenient for the driver to enter the password into his/her mobile phone while driving. Hence, it is imperative to provide a solution for overcoming the aforesaid drawbacks of the prior art, such that users need not enter a password under predetermined conditions but have to enter a password under unanticipated conditions.